Added devise gem for user authentication, as well as user model and users factory
Added Gemfile.lock to .gitignore
Added user spec for User model
Added gem shouldamatchers for validation specs
Added validation specs for User model
Added specs and show action to users controller
Added protect form forgery with null session to application controller
Removed the api subdomain, and kept it as a namespace in the routes
Added create User spec, action and endpoint
Added update User action, spec and route
Added destroy action to User controller